GAS-GENERATED EXPANDABLE BEADS AS BURNING RATE ACCELERATORS

Abstract

Mechanical enhancement of the burning rate of solid propellants is achieved by the incorporation of limited percentages of gas-generated-expandable beads into the solid propellant composition during propellant mixing and which are chemically crosslinked during propellant curing to a solid propellant grain. When the flame front reaches an individual bead during propellant grain burning, the bead which contains a blowing agent selected from 4-toluenesulfonyl hydrazide and 4,4'-oxybis(benzenesulfonyl hydrazide) and coated with a bead forming material consisting of about 95 parts by weight hydroxyl-terminated polybutadiene prepolymer, of about 5 parts by weight of trimethylolpropane, and of about 6 parts by weight of isophorone diisocyanate expands to several times its volume and ruptures. Bead expansion or rupture causes a disruption of the propellant's surface, and the flame can penetrate into the propellant. The penetration results in a major increase in burning rate. An increase in propellant density and an improvement in mechanical properties are achieved as a result of the beads being chemically crosslinked during propellant curing after being first physically dispersed in the propellant composition during propellant mixing.

Source: Google Patents

35 USC §181 Secrecy Order

Inventor

• 1DAVID C. SAYLES

Sensitive facility: Huntsville AL (NASA/Army)